1. Field of the Invention
The present invention relates to a projector with a heat insulating construction for preventing the transmission of high heat to a casing of the projector and can disperse and radiate the high heat.
2. Description of the Related Art
In these days, a data projector is used in many cases for projecting images displayed on a screen of a personal computer, images based on video signals, and images based on image data stored in a memory card on to a screen.
This data projector employs a light source unit which includes a small and highly luminous discharge lamp such as a metal halide lamp or an extra-high pressure mercury lamp. Then, light emitted from the light source unit is modulated into light of three primary colors through color filters of a color wheel. Following this, the modulated light is shone on to a liquid crystal display device or a display device referred to as a DMD (Digital Micromirror Device) via a light source side optical system which includes a light guiding unit, and the light from the display device is then projected on to a screen via a projection side optical system which includes a zooming function.
In addition, the data projector described above incorporates a plurality of heat sources such as the light source unit, the light source side optical system, a power supply circuit, the display device and the like within a projector casing. Among them, the light source unit is heated to such a high temperature that exceeds 1000° C., and therefore, the heat of the light source unit so heated is conducted to the projector casing, leading to a problem that the temperature of the projector casing is increased.
Then, the Japanese Unexamined Patent Publication No. 2008-26732 proposes a projector in which an outlet side spatial compartment where a light source unit is disposed is defined within a substantially rectangular parallelepiped projector casing. In addition, cooling spaces are formed between an upper heat insulating casing which defines the outlet side spatial compartment and the light source unit and between the upper heat insulating casing and an upper panel of the projector casing to thereby prevent the transmission of heat from the light source unit to the upper panel. Additionally, in this proposal, it is also proposed to disperse heat that is conducted from the light source unit to the upper panel by affixing an aluminum sheet to the upper panel as a heat conductive sheet.
The light source unit used in the recent projector is made highly luminous, and when it is used, the highly luminous light source unit is heated to a high temperature. Therefore, heat from the light source unit so heated is conducted to the projector casing, which increases the temperature of the projector casing, having caused a problem that a particular portion of the upper panel which lies in the vicinity of the light source unit is locally heated to a high temperature. Then, as has been described above, the proposal has been made to prevent the direct transmission of heat from the light source unit to the projector casing by defining the space between the light source unit and the projector casing. Further, it has also been proposed to realize the dispersion of heat from the light source unit by affixing the heat conductive sheet to the projector casing. However, since the temperature of the light source unit is increased to such an extent that it exceeds 1000° C., it has not been able to prevent sufficiently the particularly local increase in temperature at the portion on the upper panel of the projector casing which lies directly above the light source unit.
In addition, in the case of a metallic sheet such as the aluminum sheet being used as the heat conductive sheet, due to the fact that the metallic sheet is charged in such a way as a capacitor is done, noise has been caused to be generated. Consequently, when the metallic sheet is used as the heat conductive sheet, the heat conductive sheet cannot be laid out to spread widely over the upper panel, having led to a problem that heat conducted to the upper panel cannot be dispersed sufficiently.
Consequently, a problem that is to be solved by the invention is to provide a projector with a heat insulating construction which can prevent the transmission of high heat of a light source unit to a projector casing thereof and which can disperse and radiate the high heat.